package com.ziyun.pop.mall.base.utils;

public class Base64Util {
	 private static final int BASELENGTH = 128;
	    private static final int LOOKUPLENGTH = 64;
	    private static final int TWENTYFOURBITGROUP = 24;
	    private static final int EIGHTBIT = 8;
	    private static final int SIXTEENBIT = 16;
	    private static final int FOURBYTE = 4;
	    private static final int SIGN = -128;
	    private static char PAD = '=';
	    private static byte[] base64Alphabet = new byte[BASELENGTH];
	    private static char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];

	    static {
	        for (int i = 0; i < BASELENGTH; ++i) {
	            base64Alphabet[i] = -1;
	        }
	        for (int i = 'Z'; i >= 'A'; i--) {
	            base64Alphabet[i] = (byte) (i - 'A');
	        }
	        for (int i = 'z'; i >= 'a'; i--) {
	            base64Alphabet[i] = (byte) (i - 'a' + 26);
	        }

	        for (int i = '9'; i >= '0'; i--) {
	            base64Alphabet[i] = (byte) (i - '0' + 52);
	        }

	        base64Alphabet['+'] = 62;
	        base64Alphabet['/'] = 63;

	        for (int i = 0; i <= 25; i++) {
	            lookUpBase64Alphabet[i] = (char) ('A' + i);
	        }

	        for (int i = 26, j = 0; i <= 51; i++, j++) {
	            lookUpBase64Alphabet[i] = (char) ('a' + j);
	        }

	        for (int i = 52, j = 0; i <= 61; i++, j++) {
	            lookUpBase64Alphabet[i] = (char) ('0' + j);
	        }
	        lookUpBase64Alphabet[62] = (char) '+';
	        lookUpBase64Alphabet[63] = (char) '/';

	    }

	    private static boolean isWhiteSpace(char octect) {
	        return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
	    }

	    private static boolean isPad(char octect) {
	        return (octect == PAD);
	    }

	    private static boolean isData(char octect) {
	        return (octect < BASELENGTH && base64Alphabet[octect] != -1);
	    }


	    /**
	     把64位byte数组转换成String
	     */
	    public static String encode(byte[] binaryData) {

	        if (binaryData == null) {
	            return null;
	        }

	        int lengthDataBits = binaryData.length * EIGHTBIT;
	        if (lengthDataBits == 0) {
	            return "";
	        }

	        int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
	        int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
	        int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1
	                : numberTriplets;
	        char encodedData[] = null;

	        encodedData = new char[numberQuartet * 4];

	        byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
	        int encodedIndex = 0;
	        int dataIndex = 0;

	        for (int i = 0; i < numberTriplets; i++) {
	            b1 = binaryData[dataIndex++];
	            b2 = binaryData[dataIndex++];
	            b3 = binaryData[dataIndex++];

	            l = (byte) (b2 & 0x0f);
	            k = (byte) (b1 & 0x03);

	            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
	                    : (byte) ((b1) >> 2 ^ 0xc0);
	            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4)
	                    : (byte) ((b2) >> 4 ^ 0xf0);
	            byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6)
	                    : (byte) ((b3) >> 6 ^ 0xfc);

	            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
	            encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
	            encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
	            encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
	        }

	        // form integral number of 6-bit groups
	        if (fewerThan24bits == EIGHTBIT) {
	            b1 = binaryData[dataIndex];
	            k = (byte) (b1 & 0x03);

	            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
	                    : (byte) ((b1) >> 2 ^ 0xc0);
	            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
	            encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
	            encodedData[encodedIndex++] = PAD;
	            encodedData[encodedIndex++] = PAD;
	        } else if (fewerThan24bits == SIXTEENBIT) {
	            b1 = binaryData[dataIndex];
	            b2 = binaryData[dataIndex + 1];
	            l = (byte) (b2 & 0x0f);
	            k = (byte) (b1 & 0x03);

	            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
	                    : (byte) ((b1) >> 2 ^ 0xc0);
	            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4)
	                    : (byte) ((b2) >> 4 ^ 0xf0);

	            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
	            encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
	            encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
	            encodedData[encodedIndex++] = PAD;
	        }

	        return new String(encodedData);
	    }

	    /**
	     * 把Base64位编码转换成byte数组
	     */
	    public static byte[] decode(String encoded) {

	        if (encoded == null) {
	            return null;
	        }

	        char[] base64Data = encoded.toCharArray();
	        // remove white spaces
	        int len = removeWhiteSpace(base64Data);

	        if (len % FOURBYTE != 0) {
	            return null;// should be divisible by four
	        }

	        int numberQuadruple = (len / FOURBYTE);

	        if (numberQuadruple == 0) {
	            return new byte[0];
	        }

	        byte decodedData[] = null;
	        byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
	        char d1 = 0, d2 = 0, d3 = 0, d4 = 0;

	        int i = 0;
	        int encodedIndex = 0;
	        int dataIndex = 0;
	        decodedData = new byte[(numberQuadruple) * 3];

	        for (; i < numberQuadruple - 1; i++) {

	            if (!isData((d1 = base64Data[dataIndex++]))
	                    || !isData((d2 = base64Data[dataIndex++]))
	                    || !isData((d3 = base64Data[dataIndex++]))
	                    || !isData((d4 = base64Data[dataIndex++]))) {
	                return null;
	            }// if found "no data" just return null

	            b1 = base64Alphabet[d1];
	            b2 = base64Alphabet[d2];
	            b3 = base64Alphabet[d3];
	            b4 = base64Alphabet[d4];

	            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
	            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
	            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
	        }

	        if (!isData((d1 = base64Data[dataIndex++]))
	                || !isData((d2 = base64Data[dataIndex++]))) {
	            return null;// if found "no data" just return null
	        }

	        b1 = base64Alphabet[d1];
	        b2 = base64Alphabet[d2];

	        d3 = base64Data[dataIndex++];
	        d4 = base64Data[dataIndex++];
	        if (!isData((d3)) || !isData((d4))) {// Check if they are PAD characters
	            if (isPad(d3) && isPad(d4)) {
	                if ((b2 & 0xf) != 0)// last 4 bits should be zero
	                {
	                    return null;
	                }
	                byte[] tmp = new byte[i * 3 + 1];
	                System.arraycopy(decodedData, 0, tmp, 0, i * 3);
	                tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
	                return tmp;
	            } else if (!isPad(d3) && isPad(d4)) {
	                b3 = base64Alphabet[d3];
	                if ((b3 & 0x3) != 0)// last 2 bits should be zero
	                {
	                    return null;
	                }
	                byte[] tmp = new byte[i * 3 + 2];
	                System.arraycopy(decodedData, 0, tmp, 0, i * 3);
	                tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
	                tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
	                return tmp;
	            } else {
	                return null;
	            }
	        } else { // No PAD e.g 3cQl
	            b3 = base64Alphabet[d3];
	            b4 = base64Alphabet[d4];
	            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
	            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
	            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);

	        }

	        return decodedData;
	    }

	    /**
	     * remove WhiteSpace from MIME containing encoded Base64Util data.
	     * 
	     * @param data
	     *            the byte array of base64 data (with WS)
	     * @return the new length
	     */
	    private static int removeWhiteSpace(char[] data) {
	        if (data == null) {
	            return 0;
	        }

	        // count characters that's not whitespace
	        int newSize = 0;
	        int len = data.length;
	        for (int i = 0; i < len; i++) {
	            if (!isWhiteSpace(data[i])) {
	                data[newSize++] = data[i];
	            }
	        }
	        return newSize;
	    }
}
